Delay fuse



United States Patent "@fi ice 2,892,695 DELAY FUSE David T, Zebree',; Kingston, N.Y.,- 'assignor to Hercules Powder Company, Wilmington, DeL, a corporation of Delaware N Drawing. ApplicatibnDec'emb'erfil, 1956 Serial No. 631,468 15 Claims. 01. 52-2 This invention relates to de'tonator and squib composition'sL In one aspect this invention relates to compositions especially suitable as a delay fuse in a detonator system. In another aspect this invention relates to improve-ment in firing time regularity of delay fuses containing barium peroxide and at least one of selenium, tellurium, and sulfur, by maintaining an alloy of lead and tin in the fuse. In still another aspect this invention relates to delay fuses of barium peroxide and at least one of selenium, tellurium and sulfur improved by the presence of an alloy of lead and tin.

Delay detonator caps comprise a detonating charge, an igniter charge, and a fuse through the medium of which the detonating charge is fired, the fuse being cut to such lengthas will afford desirable delay between the firing of the igniter charge and the firing of the detonating charge which efiects detonation of the explosive to be detonated. Squibs are similar to detonators except that they areempl'oyed to initiate'deflagrating explosives such as black powder when a flame-producing means is re quired. The ignition mixture serves as the flame-producing base charge as in a delay cap, a delay squib containing a fuse which serves as the medium through which the deflagrating explosive is initiated, the fuse being cut to such length as will aiford desired delay between firing of the igniter charge and the deflagration charge.

Delay fuses comprising barium peroxide and at least one of selenium, tellurium, and sulfur have had wide use in the art for some time, not only in view of their firing characteristics, but also because they fire without evolving any substantial amount of gas upon burning. This latter characteristic eliminates development of deleterious pressure within the cap to produce premature detonation and also eliminates development of gas pressure with bursting of the shell and concomitant failure of the shot.

I have found that when firing delay caps containing barium peroxide and at least one of selenium, tellurium and sulfur as the delay fuse, there are shots that occur at random, that are entirely unpredicted. These random shots occur far outside the realm of the range of spread in burning time ordinarily associated with these fuses. Random shots result in markedly inaccurate and irregular firing over and above that which results in the normal sprea in firing time inherent in delay firing. Random shots of course impair otherwise successful series firing regardless of the specific application, e.g., whether as a component of an ordinary delay cap or of a delay squib.

Spread in firing time, above referred to, is an inherent characteristic in delay fuse compositions. Variations occur among the shots to give a range of burning times referred to as spread. The narrower the spread, the more regular is the timing, and therefore any reduction in firing time spread is important to firing accuracy.

This invention is concerned with delay fuses comprising barium peroxide and at least one of selenium, tellurium and sulfur improved to provide for greater regu- Patented June .30; 1959 2 larity in timing by elimination of random shots and by a substantialreduction in spread in firing time;

-An object of this invention is to provide improved detonator and squib compositidns. Another objectisjto provide-for improved regularity of timing in firing of detonat'ors containing barium peroxide and at least oneof selenium,-tellurium and sulfur as a delay fuse. Another object isto provide for a reduction in spreadinfiring time invdel'ay fuses com-prisingbarium peroxide and at least one of selenium, tellurium and sulfur. I Still another object is to, provide for elimination of random shots in firing delay detonators containing barium peroxide and; at least one of selenium-telluriurn and sulfur as a delay fuse. Other aspects and objects will be apparent in light of the accompanying disclosure and the appended claims. v

In accordance with this inventionare provided, as n'ew compositions, bariumperoxide and at least use of 'se- 'lenium, tell urium and sulfur in proportions for burning as a delay fuse and an alloyof lead and tin'in nemesis sufficient to impart improved regularity of burning time to saidfuse. I

The invention is illustrated with reference to the following examples: u

A delay fuse of parts beriumeerexide am 25 parts selenium was fired inla series of tests, alone and with various proportions of an alloy of 83 parts lead and 15 parts tin. The results of the use showing 'fiii'n'g "time spreads are tabulated as follows Parts by'we'i iit Fi'r'in'g' Time Nlurnlaer (Milliseeonds) w ire Barium Lead-Tm Peroxide- Alloy Average Spread Selenium (85-15) (75-25) 0 380 100 38 18 a iii 28 85 15 348 40 80 20 340 40 75 25 358 40 7O 30 345 60 e5 35 291 50 '60 to 319' 30 48 52 t 353 50 A delay use of arium peroxide-seleni m, 75-125, was fired in a series (if tests {116118 With an 31103 (if 80 lead and 20 Paris fin. Several random Shots were 013- tain'ed when firing the barium peroxide and selenium alone. None were obtained in,,presen ;e of the 80/20 211163". The results of the tests are tabulated as follows:

Parts by Weight Fi in Time h N (Milliseconds) Number -umer' Y 0 re- 5332 Lead-tin Fired I mature gelomum (35-15) Avg. Spread Shots 100 None 10 135 45 s 80 20 10 30 None 1 Shot at 35, 40 and 40 milliseconds.

The foregoing examples illustrate the reduction in spread in burning time that is accomplished in accordance with this invention. Also illustrated are those shots referred to herein as random or premature shots that liave'bee ri feund'te occur when firing barium peroxideselenium delays alone and which have been eliminated in accordance with this invention.

Concentration of lead-tin alloys in the delay fuse of this invention are within a range of about 5 to 55 weight percent, the respective proportions of lead and tin in the said alloy varying generally from about 60/40 to 90/10. About 45 to 95 weight percent, comprises barium peroxide and at least one of selenium, tellurium and sulfur, the respective proportions of barium peroxide and the remaining ingredients, -i.e., at least one of selenium, tellurium sulfur, varying generally from about /90 to 90/ 10, although the delay fuse can contain lower concentrations of barium peroxide if desired, with correspondingly higher concentrations of remaining ingredients.

In accordance with one embodiment utilizing a delay fuse of this invention, is a cap shell or casing, generally copper, containing a primary detonating material, or it may contain a primer charge such as mercury fulminate and a base charge as pentaerythritol tetranitrate. Above the detonating charge is positioned a fuse charge of this invention, for example, an 85/15 barium peroxideselenium in 75/25 weight proportion to 80/20 lead-tin alloy, within an elongated metal container, generally a lead tube of such dimensions so as to give a powder with a density of between about 3.5 and about 4.6 gm. per cc. after reducing the loaded tube to any desired size. For example, to give a delay of 135 milliseconds employing the above fuse composition, the lead tube has an outside diameter of 0.256 inch and an inside diameter of about 0.110 inch and a length of about 0.090 inch. Above the fuse in the shell, for purpose of igniting it is an ignition charge, preferably a loose lead-selenium ignition powder and ignitable upon contact with a hot resistance wire. Above the ignition charge is a sulfur plug, and above the sulfur plug is a waterproof material of any desired composition, with a closing sulfur plug above the waterproof material. A pair of conductor or leg wires extend from the outside through the closed waterproof end of the shell and are joined therein by a resistance wire in contact with the ignition powder. Firing is then accomplished by passage of electric current through the bridgewire and ignition of the ignition mixture. Detonation is then accomplished following the time required for burning the delay fuse. Series firing is accomplished by connecting a plurality of such delay assemblies, each selected to fire at the end of a predetermined period of time, consonant with methods well known in the art.

I am not certain as to how the lead-tin alloy functions to eliminate random shots as illustrated herein. However, it appears that the lead-tin alloy provides for an increase in density of the fuse powder sufficiently to prevent travel of heat generated from burning the ignition mixture through the delay fuse to the primer charge to cause premature detonation. The presence of the leadtin alloy does not, in any way, impair the burning of the fuse, while at the same time it provides reduced spread in firing time and elimination of random shots as demonstrated.

The barium peroxide-selenium, tellurium, sulfur, lead and tin components of the delay fuses of this invention are each finely divided powders, by which it is meant that their particle size is characteristic of those of ignition and delay fuse compositions of the art, for example, such that the over-all particle size of the resulting delay composition is in a range say from 1 to 70 microns.

The presence of the lead-tin alloy in the fuse composition of this invention provides for markedly improved flow of the fuse powder, the preferred degree of fineness of the alloy powder for that purpose being such that substantially all will pass through a 200 mesh screen and at least 80 percent through a 325 mesh screen.

As will be evident to those skilled in the art, various modifications can be made or followed, in the light of .4 the foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure or from the scope of the claims.

What I claim and desire to protect by Letters Patent is:

l. A new composition consisting essentially of barium peroxide and at least one fuel selected from the group consisting of selenium, tellurium and sulfur in proportions for burning as a delay fuse and from 5 to 55 weight percent of an alloy of lead and tin.

2. In a composition of claim 1, said alloy containing lead and tin in respective weight proportions in the range of about 60/40 to 90/10.

3. In a composition of claim 1, the respective weight proportions of barium peroxide and fuel being in the range of 10/90 to 90/10.

4. A composition of claim 1 wherein said fuel is tellurium.

5. A composition of claim 1 wherein said fuel is sulfur.

6. A composition of claim 1 wherein said fuel is selenium.

7. A composition of claim 1 wherein said composition has a particle size within the range of 1 to 70 microns.

8. As a new composition a finely divided mixture consisting essentially of barium peroxide and at least one fuel selected from the group consisting of selenium, tellurium and sulfur and from 5 to 55 weight percent of an alloy of lead and tin, the respective Weight proportions of said lead and tin being in the range of 60/40 to 90/ 10 and the respective weight proportions of said barium peroxide and said fuel being in the range of 10/ 90 to 90/ 10, and the particle size of said composition being within the range of 1 to 70 microns.

9. In a blasting cap containing a delay fuse together i with means for initiating burning of said delay fuse and a charge adapted to be initiated subsequent to burning of said fuse by heat from said burning, a finely divided mixture consisting essentially of barium peroxide and at least one fuel selected from the group consisting of selenium,

' 1 tellurium and sulfur in proportions for burning as said delay fuse and from 5 to weight percent of an alloy of tin and lead.

10. In a blasting cap of claim 9, the respective weight proportions of said lead and tin being within the range of /40 to 90/ 10 and the respective weight proportions of said barium peroxide and said fuel being in the range of 10/90 to 90/ 10, and the particle size of said mixture being within the range of 1 to microns.

11. A blasting cap of claim 9 wherein said delay fuse is a barium peroxide/selenium-lead/tin alloy mixture.

12. A blasting cap of claim 10 wherein said delay fuse is a barium peroxide/selenium-lead/tin alloy mixture.

13. As a delay fuse composition, a finely divided mixture consisting essentially of barium peroxide and selenium in respective weight proportions in the range of 10/90 to 10 and from 5 to 55 weight percent of an alloy of lead and tin in respective weight proportions in the range of 60/40 to 90/10.

14. A delay fuse composition of claim 13 characterized by a particle size within the range of 1 to 70 microns.

15. A delay fuse mixture consisting essentially of barium peroxide and selenium and from 5 to 55 weight percent of a finely divided alloy of tin and lead.

References Cited in the file of this patent UNITED STATES PATENTS 2,123,691 Burrows et a1. July 12, 1928 2,168,030 Holmes Aug. 1, 1939 2,363,569 Caldwell et a1 Nov. 28, 1944 2,478,918 Hale Aug. 16, 1949 

1. A NEW COMPOSITION CONSISTING ESSENTIALLY OF BARIUM PEROXIDE AND AT LEAST ONE FUEL SELECTED FROM THE GROUP CONSISTING OF SELENIUM, TELLURIUM AND SULFUR IN PROPORTIONS FOR BURNING AS A DELAY FUSE AND FROM 5 TO 55 WEIGHT PERCENT OF AN ALLOY OF LEAD AND TIN. 